In vitro penetration and subchronic toxicity of alpha-methyl-1,3-benzodioxole-5-propionaldehyde.

alpha-Methyl-1,3-benzodioxole-5-propionaldehyde (methyl-3,4-methylene-dioxy-hydrocinnamic Aldehyde, MMDHCA) is a widely used commercially available fragrance material. Because of the wide range of product availability, there is dermal exposure associated with its use. The objective of this study was to determine the in vitro human skin absorption of (14)C MMDHCA and subchronic toxicity of the material. Twenty mL of a 1% solution of radiolabeled MMDHCA in ethanol was applied to the surface of epidermal membranes isolated from full thickness human skin samples and placed in diffusion cells. Samples of the receptor fluid (50% ethanol/water) were harvested at 2, 8, 24, and 48 h and analyzed by liquid scintillation chromatography to assess dermal absorption. At 24 and 48 h, respectively, 42% and 50% of the applied dose of MMDHCA had permeated the human skin in vitro. Only 67% of the applied dose was recovered by 48 h. For the subchronic toxicity, MMDHCA was applied dermally once daily to male and female Sprague-Dawley rats (15/sex/group) at 50, 150, or 300 mg/kg/day (0.043, 0.129, or 0.259 mL/kg/day applied neat to 5 cm(2) dorsal skin) for at least 90 consecutive days. A control group (15/sex) was given vehicle (reverse osmosis water) at 0.259 mL/kg/day for a similar duration. Rats were necropsied at the end of treatment (10/sex/group) or following a 4-week recovery period (5/sex/group). The following parameters were evaluated: dermal irritation, estrous cycle, ophthalmologic examinations, body weight, feed consumption, hematology, blood coagulation, serum chemistry, organ weights, macroscopic and histopathologic examinations, and male reproductive assessment. No test article-related mortalities or effects on, estrous cycles, ophthalmic exams, mean body weights, mean body weight change, feed consumption, absolute or relative organ weights, macroscopic observations, or male reproductive morphology/function were observed. MMDHCA-related dermal irritation was observed across all dose levels with increased incidence and severity at 300 mg/kg/day. Dermal irritation that initially ranged from slight to marked improved to slight or resolved completely during the recovery phase. Based on the findings in this study, it can be concluded that (1) MMDHCA exhibits moderately high human skin permeation; (2) the NOEL for dermal irritation is below 50mg/kg/day when applied undiluted to 5 cm(2) dorsal skin and (3) the NOEL for systemic toxicity is greater than 300 mg/kg/day. During the 4-week recovery period of the 90-day study, the animals had largely recovered from MMDHCA induced dermal irritation and the associated microscopic findings.

Implications of dealing with airborne substances and reactive oxygen species: what mammalian lungs, animals, and plants have to say?

A gas-exchange structure interacts with the environment and is constantly challenged by contaminants that may elicit defense responses, thus compromising its primary function. It is also exposed to high concentrations of O(2) that can generate reactive oxygen species (ROS). Revisiting the lung of mammals, an integrative picture emerges, indicating that this bronchi-alveolar structure deals with inflammation in a special way, which minimizes compromising the gas-exchange role. Depending on the challenge, pro-inflammatory or antiinflammatory responses are elicited by conserved molecules, such as surfactant proteins A and D. An even broader picture points to the participation of airway sensors, responsive to inflammatory mediators, in a loop linking the immunological and nervous systems and expanding the role played by respiratory organs in functions other than gas-exchange. A byproduct of exposure to high concentration of O(2) is the formation of superoxide ( ), hydrogen peroxide (H(2)O(2)), hydroxyl radical (HO(•)), and other ROS, which are known to be toxic to different types of cells, including the lung epithelium. A balance between antioxidants and oxidants exists; in pulmonary epithelial cells high intracellular and extracellular levels of antioxidants are found. Antioxidant adaptations related to plant and animal life-styles involve a broad range of overlapping strategies based on well-conserved molecules. Glutathione (GSH) is an abundant and ubiquitous thiol-tripeptide antioxidant, also present in lungs, whose role in providing information on the intracellular redox state of animals and plants is well established. In these organisms, GSH influences gene expression associated with stress, maximizing defense responses. Several enzymatic antioxidants, such as glutathione peroxidase (GPx), glutathione reductase, glutathione S-transferase, and glucose 6-phosphate dehydrogenase participate in the redox system; in animals that are stress-tolerant GPx is a key element against oxidative assaults. Most importantly, alternative roles of ROS as signaling molecules have been found in all plants and animals. For example, alveolar macrophages produce that act as second messengers, in addition to having a bactericidal role. The nonradical ROS H(2)O(2) signals inflammation in mammalian lungs, apoptosis in different animal tissues, and is also involved in stomatal closure, root development, gene expression, and defense responses of plants. Antioxidant adaptations in some water-breathing animals involve the excretion of H(2)O(2) by diffusion through gas-exchange structures. The fine balance among a multitude of factors and cells makes the difference between damage and protection in animals and plants. Knowledge about the mechanisms and consequences of these molecular interactions is now starting to be integrated.

Evaluation of the developmental toxicity of acetyl cedrene.

The developmental toxicity of acetyl cedrene (AC), a widely used fragrance ingredient, was evaluated in pregnant Sprague-Dawley rats (25/group). Gavaged dosages of 0 (corn oil), 25, 50, or 100 mg/kg/day were administered on days 7 through 17 of gestation (GDs 7 to 17). First and last day dosing suspensions were analyzed for AC content. All rats were observed daily for viability, clinical signs, abortions, and premature deliveries. Body weights were recorded at frequent intervals. Cesarean-sectioning and necropsy examinations were performed on GD 21. Uteri were examined for number and distribution of implantations, live and dead fetuses, and early and late resorptions. The number of corpora lutea in each ovary was also recorded. Fetuses were weighed and examined for gender and gross external changes and soft tissue or skeletal alterations. Totals of 25, 23, 21, and 24 rats became pregnant in the 0 (control), 25, 50 and 100 mg/kg/day groups, respectively, and analysis of dosage preparations verified that administered dosages reflected calculated dosages +/-10%. No deaths or premature deliveries occurred in the study. Clinical signs included excessive salivation, which was attributed to the administration of AC. When compared to controls, significant reductions in feed consumption and body weight gains occurred only at 100 mg/kg/day. Both absolute (g/day) and relative (g/kg/day) feed consumption values were significantly decreased on GDs 7 to 12. Relative values were decreased significantly on GDs 15 to 18. Body weight gains were significantly reduced on GDs 7 to 10. Mean maternal body weights remained significantly lower than controls on GDs 9 to 14, but a marked compensatory increase in feed consumption on GDs 15 to 18 prevented further deterioration in body weight gains. No cesarean-sectioning or litter parameters were affected by dosages of AC and necropsy of the dams after cesarean section did not reveal any gross changes attributable to AC. No gross external, soft tissue, or skeletal fetal alterations (malformations or variations) were attributed by dosages AC. The average number of ossifications sites per fetus per litter did not differ among the groups. Based on these data, maternal and developmental no-observable-adverse-effect levels (NOAELs) of 50 and 100 mg/kg/day, respectively, were established for AC.

The effects of vehicles on the human dermal irritation potentials of allyl esters.

Allyl esters, frequently used in the fragrance industry, often contain a certain percentage of free allyl alcohol. Allyl alcohol is known to have a potential for delayed skin irritation. Also present in the finished product are different solvent systems, or vehicles, which are used to deliver the fragrances based upon their intended application. This study was conducted to determine whether different vehicles affect the skin irritation potential of five different allyl esters. The allyl esters tested were allyl amyl glycolate, allyl caproate, allyl (cyclohexyloxy)acetate, allyl cyclohexylpropionate, and allyl phenoxyacetate in the vehicles diethyl phthalate, 3:1 diethyl phthalate:ethanol, and 1:3 diethyl phthalate:ethanol at concentrations of 0.1%, 0.5%, 1.0%, and 2.0% (w/w). A modified cumulative irritation test was conducted in 129 human subjects. Test materials (0.3 ml) were applied under occlusion to skin sites on the back for 1 day (24 h) using Hill Top chambers. Irritation was assessed at 1, 2, 4, and 5 days following application of test materials. Cumulative irritation scores varied considerably among test materials. There were no delayed irritation observations. The highest irritation scores were observed at the 2.0% concentration for all test materials. The irritation scores for allyl amyl glycolate, allyl (cyclohexyloxy)acetate, and allyl phenoxyacetate were highest in 1:3 diethyl phthalate:ethanol, thus the resulting calculated no-observed-effect levels, 0.12%, 0.03%, and 0%, respectively, were much lower for this vehicle compared to the diethyl phthalate vehicle, 0.33%, 0.26%, 0.25%, respectively. These data showed a trend for lower concentration thresholds to induce irritation when higher levels of ethanol were used in the vehicle.

Simulated inhalation levels of fragrance materials in a surrogate air freshener formulation.

This study measured postapplication exposure levels of fragrance materials in a surrogate air freshener formulation in an environmentally-controlled exposure room (ECER). A five-s spray was released to simulate normal consumer use conditions. Time-course airborne fragrance material levels were sampled with Tenax tubes, and aerosol size distributions were monitored with a TSI 3320 aerodynamic particle sizer. Triplicate experiments were performed for each of the control/test substances. The control substance (unfragranced formulation) experiments indicated that the airborne fragrance materials were not detected, suggesting that the base propellant formulation did not interfere with the sampling procedure or analytical results. The test substance experiments found that the higher the volatility of the fragrance material, the higherthe airborne fragrance concentration within the ECER. In the adult breathing zone height, the maximum concentrations of the nine fragrance materials ranged from 108 to 347 microg/m3 during the first minute postapplication. In the child breathing zone height, the maximum fragrance material concentrations ranged from 125 to 362 microg/m3 during 2-6 min postapplication. Particle size distributions indicated that approximately 60-70% of the generated aerosols were less than 1 microm aerodynamic diameter. Initial peak particle mass concentrations (<5 microm) were 800-1000 microg/m3 during the first minute postapplication. Following initial peak concentrations, there was approximately 10-15 min of fluctuation, and then particle levels decayed gradually and exponentiallyto near background levels. Exposure to the test formulation would originate from two components: particle-bound and vapor-phase fragrance materials. Particle-bound fragrance exposure accounted for approximately 47% and 72% of the total exposures during the first minute postapplication period in the adult and child breathing zone heights, respectively.